The proposed research involves a study of lens regeneration from the iris and neural retina regeneration from the pigmented, retinal epithelium in urodele amphibians. It is hoped to obtain information concerning the stimuli which release these metaplasias and the role of trophic factors during regeneration. Synthesis of macromolecules and cytological changes in the reacting tissues will also be studied. Some of the aspects to be investigated are the ultrastructural changes taking place in lens capsule formation and the incorporation of 3H-fucose into the glycoproteins of the capsule. Incorporation of 3H-fucose into ciliary retina and plexiform layers of the neural retina during lens regeneration will also be studied. Investigations on neural retina regeneration from the pigmented retina of newt and salamander larvae under several conditions of isolation in the eye and in the fin mesenchyme will be continued. The role of growth factors and spinal ganglia in stimulating lens regeneration in organ culture of irideo-corneal complexes and the incorporation of 3H-thymidine into DNA and 35S-methionine into proteins in these regenerates will be followed. Isolation of crystallins from normal and regenerating lenses with SDS-urea polyacrylamide gel electrophoresis is in progress and, if successful, will be used to analyze the lenses regenerating in culture.